近日，我校植物科学技术学院低碳稻作团队利用13C同位素示踪技术，探明了稻菇模式通过利用秸秆栽培食用菌促进土壤外源碳固定，减少稻田甲烷排放的机理。
低碳稻作模式关系到“双碳”目标的达成，传统稻作模式秸秆还田虽可减少焚烧产生的碳排放和环境污染，并向土壤输入外源碳等养分，但冬季气温低水稻秸秆降解慢，秸秆碳有很大比例以温室气体等形态流失，土壤碳库固定量有限。另外秸秆腐解不及时也会减少后茬作物种子与土壤的接触，不利冬季作物出苗，并为病虫越冬提供有利生存环境。食用菌可以秸秆为基质获取养分进行生长，其菌丝体在促进秸秆降解的同时可促进土壤团聚体层级结构发育。在秋冬季利用秸秆栽培菌菇的新型稻作模式，因其较高的周年生产收益目前在湖北、湖南、江西、四川等省份大面积推广应用。为完善秸秆管理、加强稻田土壤碳汇功能、促进稻田生产碳中和，我校植物科学技术学院低碳稻作团队联合东北农业大学土壤保护与修复重点实验室，利用13C同位素示踪技术，对稻菇模式菌丝生长对土壤团聚体秸秆碳固定和碳库化学特性的影响机制开展了研究工作。
接种食用菌对秸秆堆肥土壤碳库转化分析
团队开展了稻菇模式四种食用菌接种量对秸秆外源碳转化的影响研究，在大田试验初期，通过13CO2脉冲标记制备13C标记秸秆。试验结果显示，秸秆接种食用菌还田后，土壤真菌和菌丝体丰度显著升高，菌丝生长促进了秸秆外源碳向土壤有机碳库的输入，显著降低外源碳甲烷转化比例。与此同时，食用菌菌丝生长显著降低了土壤有机碳库芳香性，促进了土壤小团聚体胶结，加快土壤团聚体层级结构发育，加强土壤团聚体固碳能力。秸秆外源碳在土壤中的固存率与接种量正相关，食用菌菌丝体对土壤结构起到了保护作用，在本研究中食用菌接种量为3000 kg/hm2时，秸秆堆肥外源碳土壤碳库转化比例最高，甲烷转化量最低。
研究结果以“The rice-edible mushroom pattern promotes the transformation of composted straw-C to soil organic carbon”为题发表在Agriculture Ecosystems & Environment 期刊上。华中农业大学植物科学技术学院博士生胡权义为论文第一作者，东北农业大学刘天奇副教授为通讯作者，华中农业大学曹凑贵教授、黄见良教授、李成芳副教授等老师和河南大学丁会纳博士参与了该研究的指导。该研究得到“十四五”国家重点研发计划“长江中下游坡耕地红黄壤与中低产稻田产能提升技术模式及应用”项目（2021YFD1901205）、国家自然科学基金（32272230）和中国博士后科学基金（2020M672373）资助。
英文摘要：
The application of composted straw in conventional rice cultivation patterns can enhance soil organic carbon (SOC); however, it increases methane (CH4) emission, thereby reducing its net carbon sequestration efficiency in paddy fields. The rice–edible mushroom pattern may improve this phenomenon because edible mushrooms can promote straw decomposition and soil aggregate formation. Here, we investigated the effect of four inoculation amounts of edible mushroom on the transformation of composted straw-C in paddy fields using13C tracer technology under rice–edible mushroom pattern. The results indicated that the inoculation of edible mushrooms increased the abundance of soil microorganisms and fungal mycelium, reduced SOC aromaticity, and promoted the formation of macroaggregates. Inoculation of edible mushrooms stimulated the transformation of composted straw-C to SOC and reduced its conversion to CH4. The sequestration efficiency of composted straw-C in the soil increased as the inoculation amounts of edible mushrooms increased. When the edible mushroom inoculation amount was 3000 kg ha–1, the highest amount of composed straw-C was sequestrated in soil. With more inoculation amount, more fungal mycelium was produced, which enhanced the physical protection of composted straw-C by promoting the formation of soil aggregates. This study indicated that under the rice–edible mushroom pattern, transformation of composted straw-C to the soil carbon was favored compared with its transformation to CH4, and this conversion efficiency increased with the increasing inoculation amounts of edible mushrooms.
论文链接：https://doi.org/10.1016/j.agee.2023.108560
